2010-02-16  Richard Guenther  <rguenther@suse.de>

	* alias.c (memrefs_conflict_p): Distinguish must-alias from
	don't know.
	(true_dependence): If memrefs_conflict_p computes must-alias
	trust it.  Move TBAA check after offset-based disambiguation.
	(canon_true_dependence): Likewise.

From-SVN: r156797